1. Field of the Invention
The present invention relates to a method for preparing a Eucalyptus extract, and, more specifically, to method for preparing a Eucalyptus extract wherein an essential oil constituent is removed from a Eucalyptus plant, the residue is extracted with water or an organic solvent aqueous solution, and the obtained extract residue is further extracted with an organic solvent aqueous solution or an organic solvent, whereby macrocarpals in high yield are obtained.
2. Description of the Related Art
A Eucalyptus plant is a tall tree native to Australia and New Zealand and also cultivated in many parts of Japan. The essential oil obtained from the leaves (Eucalyptus oil) has a sensation of coolness and is used in medicine for a nasal catarrh and bronchial catarrh and also in an adhesive skin patch, dentifrice, insect deterrent, and the like. The plant is characterized by a very high growth rate and is therefore suitable for the substance production. Conventionally, new macrocarpals and method of preparation thereof is known, characterized in that an effective physiological active substance is isolated from the extract of Eucalyptus and the partial chemical structure is determined and named as macrocarpals and also obtained from a Eucalyptus plant (Japanese Patent Publication No. 3365782). Also, it is known that when extracting an effective to prevent and treat both of caries and periodontal disease, an essential oil component (Eucalyptus oil) is removed from a Eucalyptus plant, the residue is extracted with a polar solvent, the obtained extract and a phloroglucinol derivative contained in the extract have an extremely strong antibacterial activity against bacteria causing caries and periodontal disease as well as an inhibiting effect on collagenase produced by the periodontal disease causative bacteria Porphyromonas gingivalis (Japanese Patent Publication No. 2804232).
As thus described, the Eucalyptus extract has various kinds of effects such as an antibacterial effect and anti-inflammatory effect as well as a ceramide production promoting effect and quality improvement of hair. The Eucalyptus extract has a very unique and very strong odor that can be sensed even if the blending amount of the extract is very small. Therefore, when the extract is used for cosmetics, as a medical product, or as a quasi-drug and the like, various challenges were addressed to the problem that a sufficient amount to be effective could not be blended. For example, with regard to a method for producing a Eucalyptus extract, a producing method is known wherein a ratio of 1,8-cineole—which is known to be a Eucalyptus-specific odor causative substance—to Macrocarpal A is regulated to reduce the odor (Patent Publication No. 2006-036672). Another method is known wherein a color and an odor are removed from a solution of an extract prepared by extracting a Eucalyptus plant with a polar solvent by using an adsorbent (Patent Publication No. 2001-348307). On the other hand, a method for producing polyphenol compounds is known, wherein a Eucalyptus plant material is subjected to an extraction treatment with water at low temperature, thereafter the residue is subjected to a further extraction treatment with an aqueous alkaline solution, and the extract aqueous solution at low temperature mentioned in the above is treated with the addition of an adsorbent, thereafter the treatment solutions obtained from the extraction residues and the extract aqueous solution are then mixed together to obtain the active ingredient of the plant material in high yield (Patent Publication No. 2000-256345).
As thus described, various methods to prepare a Eucalyptus extract are known. However, to achieve a simplified step with a high concentration of macrocarpals as an effective ingredient in high yield is difficult, and also the obtained extract is unsatisfying with regard to taste, appearance, and other properties, as well as poor in versatility.